260 MICRO-ORGANISMS AND FERMENTATION. 



The cylinder B is surrounded by a cast-iron jacket made in 

 two parts ; the upper portion serves as a water-jacket for 

 cooling the wort and for regulating the fermentation ; the 

 lower portion is used as a steam-jacket, and is provided with a 

 cock at for the entrance of the steam, and another at S for 

 the outlet. M is a ring-shaped tube provided with small holes ; 

 this is connected with the cold-water main during the cooling 

 of the wort ; the water flows out at N. The stirrer J is set in 

 motion by means of toothed gear. The height of the liquid 

 in the cylinder is indicated by means of a float, connected with 

 which is a pointer and arc L. Connected with the top of 

 the cylinder is the bent tube K. At the bottom is the cock Q, 

 which is in connection with the pipe b. Both the bent tubes 

 dip into the vessel E, which is filled with water. 



The wort is introduced into the lower cylinder, where it is 

 treated in the ordinary manner. The pure culture is intro- 

 duced into the upper cylinder, and is then washed down 

 into the lower cylinder by means of a little wort, which 

 is forced from B into A, and then back again into B. When 

 a vigorous multiplication of the yeast has set in, the liquid is 

 stirred up, and a portion forced into A ; this is to be used to 

 start the next fermentation. The cylinder B thus serves 

 alternately as fermenting-cylinder and wort- cylinder. 1 



Other modifications have been devised by BROWN and 

 MORRIS, ELION, KOKOSINSKI, and VAN LAER; more widely 

 different are the forms devised by P. LINDNER and MARX. 2 



1 Both the forms of apparatus described above are manufactured by Messrs. 

 BURMEISTER and WAIN, of Copenhagen ; HANSEN and KUEHLE'S apparatus is 

 also made by W. E. JENSEN, of Copenhagen. 



2 An apparatus which has now become of considerable importance as part of 

 HANSEN'S system of pure yeast cultivation is the closed cooler mentioned above, 

 by means of which it is possible to introduce the wort into the fermenting- 

 vessel absolutely pure and properly aerated. Appliances having this for their 

 object were devised by VELTEN shortly after the publication of Pasteur's Etudes, 

 and were constructed in accordance with PASTEUR'S theoretical views, but at 

 that time they could not acquire any practical importance ; for what was the 

 use of having a pure wort when the disease-germs were again introduced with 

 the yeast? The construction of the Velten apparatus was also rather 

 objectionable, incandescent tubes being used for sterilising the air. A model 

 construction is found, on the contrary, in the Old Carlsberg apparatus, in 

 which the air is sterilised through cotton- wool. The conditions which render 



